This invention relates to novel enteral contrast media useful for proton nuclear spin tomography (proton NMR diagnosis).
Nuclear spin tomography has developed into a novel and very efficient imaging method for diagnostic purposes, superior to the known diagnostic methods (e.g., X-ray diagnostics, X-ray computerized tomography etc.) in solving certain diagnostic problems.
One advantage of nuclear spin tomography is its excellent suitability for differentiation of tissues. The information content of the image is significantly enhanced by the use of contrast media in nuclear spin tomography. In this connection, novel, iodine-free contrast media, in part used in very low doses, can be utilized. These are substantially more compatible than iodine-containing contrast media. The contrast media lending themselves to nuclear spin tomography exhibit the property, due to their paramagnetism, of affecting the relaxation times T.sub.1 (spin-lattice) and T.sub.2 (spin-spin) of the hydrogen atoms present in body water in such a way that imaging when using a nuclear spin tomograph is substantially improved.
However, since the possibility of obtaining an image of tissues by nuclear spin tomography exists only if there are sufficient hydrogen atoms (water, fat), body cavities can be reproduced by nuclear spin tomography only if they are filled with an adequate amount of water or fat and if this liquid quantity can be maintained within the area to be diagnosed during the imaging period. Similarly, only in this case is it possible for the paramagnetic contrast medium to deploy its effect. The heretofore described contrast media for nuclear spin tomography are suitable only for imaging tissues having adequate water or fat content.